Would it be correct to call Thanatos's emotionless state a blessing in this case? Before, he would have reacted in panicked horror as Buttercup slips from his grip. Now, there is no moment spared for it. Go.

Thanatos dives, flapping his wings once before folding them tight against his body. Buttercup's scream pierces the air whistling past his ears. Only when he's near does he reach out to pull her against his chest his chest. They fall together a bit longer. Then night-sky wings unfurl, and he angles them so that they swoop up away from the approaching ground. It will still take him another moment to slow their flight and stabilize.